My friend and I do this often for making DVDs that we then send to the band. It's a great way to get pre-approval for video taping.

Anyway, I'm not sure what the technical terms are, but I'm sure it's what the other people here have said. He basically keeps an eye on the levels when the band starts playing, and his camera fortunately lets you adjust the recording volume in order to adjust for these high volumes. This way, we were able to be in the very front of the stage for a Mudhoney show and not have any distortion in the sound.

That said, he's still not satisfied with the audio quality. My friend is a big audio guy who runs sound for bands from time to time, and he knows how to record properly. For the next shows we do we're going to try for advance approval to patch into the soundboard with some sort of recording device.